In recent years, development in electronics-related techniques has resulted in the rapid spread of information-processing apparatuses and electronic office apparatuses.
When a large number of electronic apparatuses are operated, there frequently occur electromagnetic disturbance of apparatuses caused by the noise generated by electronic parts in the vicinity thereof, misoperation caused by electrostaticity, and other problematic phenomena, and such problems have become more serious.
In order to solve these problems, there is demand for a material exhibiting an excellent conductive (antistatic) property and charge-controllability.
Hitherto, there have been widely employed conductive polymer materials which are provided through incorporating a conductive filler or a similar material into a polymer material exhibiting low electrical conductivity.
Generally employed conductive fillers are metallic fiber, metallic powder, carbon black, carbon fiber, etc. When metallic fiber or metallic powder is used as a conductive filler, excellent conductivity is attained, but the materials containing such a conductive filler exhibit poor corrosion resistance and mechanical strength, which is problematic.
When carbon black is used as a conductive filler, conductive carbon black products attaining high conductivity through addition in a small amount such as Ketjen Black, Vulcan XC72, and Acetylene Black are employed. However, these carbon black products have poor dispersibility in resin.
Such poor dispersibility of carbon black affects the conductivity of the resin composition, and tailored blending and mixing techniques are essential for attaining consistent conductivity.
When carbon fiber is used as a conductive filler, a conventional reinforcing carbon fiber realizes desired strength and elastic modulus. However, in order to attain satisfactory conductivity, such a filler must be charged at high density, resulting in impairment in intrinsic physical properties of resin.
In addition, in the production of molded products with a complex shape, the conductive filler is localized in the products, causing unsatisfactory variation of conductivity in each product.
Among carbon fiber products, a fiber product having a smaller diameter provides a larger contact area between resin and fiber filaments as compared with the case where a fiber product having a larger diameter is used in the same amount, and is a promising conductivity-imparting agent.
For example, an ultrafine carbon fibril exhibiting excellent conductivity is disclosed (see, for example, Patent Document 1).
However, in mixing with a resin, dispersibility of the carbon fibril is unsatisfactory, and appearance of the molded products is unsatisfactorily impaired.
When a resin is colored by use, as a coloring agent, of a known carbon black product for pigment use, the product must be used in a large amount so as to develop black color. Therefore, such a carbon black is problematic in terms of dispersibility in resin and appearance of molded products.
Although an approach of addition of an ultrafine carbon fibril is disclosed (see, for example, Patent Document 2), the document never teaches the flame retardancy attributable to the ultrafine carbon fibril.
Since the flame retardancy attained in the disclosed approach is unsatisfactory, the approach cannot be employed for resin products requiring high flame retardancy.
Also known is a resin composition containing a thermoplastic resin, carbon nanotube, and at least one compound selected from among a phosphorus compound, a phenol compound, an epoxy compound, and a sulfur compound (see, for example, Patent Document 3). The Examples in the document merely discloses a polycarbonate resin/acrylonitrile-butadiene-styrene resin, and never discloses a polycarbonate resin/side-chain crystalline polymer.
Furthermore, when carbon nanotube is used in a large amount in order to attain conductive performance, appearance of the molded product is impaired, and impact resistance is lowered. The document does not disclose improvement in solvent resistance.
Conventional polycarbonate resin/polyolefin-based resin alloys have poor compatibility. Therefore, impact resistance is unsatisfactory, and the molded products thereof undergo laminar peeling, thereby impairing the product appearance. Thus, incorporation of a compatibilizer or a similar agent is essential.
According to conventional techniques, moldability such as mold-releasability cannot be enhanced, and a releasing agent or a similar agent is generally added to resin. Therefore, enhancement in releasability is unsatisfactory, and heat resistance and impact resistance may be lowered.
When carbon nanotube is used in a large amount, in some cases, flow characteristics is impaired, and moldability lowers considerably.
Furthermore, when carbon nanotube is added to a thermoplastic resin for general use, dispersion of carbon nanotube is unsatisfactory. When compounding is performed under severe conditions, carbon nanotube is broken. In other words, a large amount of carbon nanotube for attaining conductivity causes impairment of appearance and physical properties of molded products, or an increase in viscosity, thereby failing to form molded products.    [Patent Document 1]    Japanese Kohyo Patent Publication No. 62-500943    [Patent Document 2]    Japanese Patent Application Laid-Open (kokai) No. 3-74465    [Patent Document 3]    Japanese Patent Application Laid-Open (kokai) No. 2004-182842